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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Tailored Core Shell Cathode Powders for Solid Oxide Fuel Cells

In this Phase I SBIR project, a “core-shell” composite cathode approach was evaluated for improving SOFC performance and reducing degradation of lanthanum strontium cobalt ferrite (LSCF) cathode materials, following previous successful demonstrations of infiltration approaches for achieving the same goals. The intent was to establish core-shell cathode powders that enabled high performance to be obtained with “drop-in” process capability for SOFC manufacturing (i.e., rather than adding an infiltration step to the SOFC manufacturing process). Milling, precipitation and hetero-coagulation methods were evaluated for making core-shell composite cathode powders comprised of coarse LSCF “core” particles and nanoscale “shell” particles of lanthanum strontium manganite (LSM) or praseodymium strontium manganite (PSM). Precipitation and hetero-coagulation methods were successful for obtaining the targeted core-shell morphology, although perfect coverage of the LSCF core particles by the LSM and PSM particles was not obtained. Electrochemical characterization of core-shell cathode powders and conventional (baseline) cathode powders was performed via electrochemical impedance spectroscopy (EIS) half-cell measurements and single-cell SOFC testing. Reliable EIS testing methods were established, which enabled comparative area-specific resistance measurements to be obtained. A single-cell SOFC testing approach also was established that enabled cathode resistance to be separated from overall cell resistance, and for cathode degradation to be separated from overall cell degradation. The results of these EIS and SOFC tests conclusively determined that the core-shell cathode powders resulted in significant lowering of performance, compared to the baseline cathodes. Based on the results of this project, it was concluded that the core-shell cathode approach did not warrant further investigation.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2014

Assessment of simulated water balance from Noah, Noah-MP, CLM, and VIC over CONUS using the NLDAS test bed

This study assesses the hydrologic performance of four land surface models (LSMs) for the conterminous United States using the North American Land Data Assimilation System (NLDAS) test bed. The four LSMs are the baseline community Noah LSM (Noah, version 2.8), the Variable Infiltration Capacity (VIC, version 4.0.5) model, the substantially augmented Noah LSM with multiparameterization options (hence Noah-MP), and the Community Land Model version 4 (CLM4). All four models are driven by the same NLDAS-2 atmospheric forcing. Modeled terrestrial water storage (TWS), streamflow, evapotranspiration (ET), and soil moisture are compared with each other and evaluated against the identical observations. Relative to Noah, the other three models offer significant improvements in simulating TWS and streamflow and moderate improvements in simulating ET and soil moisture. Noah-MP provides the best performance in simulating soil moisture and is among the best in simulating TWS, CLM4 shows the best performance in simulating ET, and VIC ranks the highest in performing the streamflow simulations. Despite these improvements, CLM4, Noah-MP, and VIC exhibit deficiencies, such as the low variability of soil moisture in CLM4, the fast growth of spring ET in Noah-MP, and the constant overestimation of ET in VIC.

Cai, Xitian↗
DOE OSTI2019

Metal-Supported Solid Oxide Electrolysis Cell with Significantly Enhanced Catalysis

High-temperature electrolysis (HTE) using solid oxide electrolysis cells (SOECs) is a promising hydrogen production technology and has attracted substantial research attention over the last decade. While most studies are conducted on hydrogen electrode-supported type cells, SOEC operation using metal-supported cells has received minimal attention. The development of metal-supported SOECs with performance similar to the best conventional SOECs is reported. These cells have stainless steel supports on both sides, 10Sc1CeSZ electrolyte and electrode backbones, and nano-structured catalysts infiltrated on both hydrogen and oxygen electrode sides. Samarium-doped ceria (SDC) mixed with Ni is infiltrated as a hydrogen electrode catalyst, and the effect of ceria:Ni ratio is studied. On the oxygen electrode side, catalysts including lanthanum strontium manganite (LSM), lanthanum strontium cobalt ferrite (LSCF), praseodymium oxide (Pr 6 O 11 ), and their composite catalysts with SDC (i.e., LSM-SDC, LSCF-SDC, and Pr 6 O 11 -SDC) are compared. Utilizing the materials with highest catalytic activity (Pr 6 O 11 -SDC and SDC40-Ni60) and optimizing the catalyst infiltration processes, excellent electrolysis performance of metal-supported cells is achieved. Current densities of –5.31, –4.09, –2.64, and –1.62 A cm –2 are accomplished at 1.3 V and 50 vol% steam content at 800, 750, 700, and 650 °C, respectively.

08 HYDROGEN↗
DOE OSTI2013

Three-Dimensional Reconstruction and Microstructure Modeling of Porosity-Graded Cathode Using Focused Ion Beam and Homogenization Techniques

In this study, microstructure of a porosity-graded lanthanum strontium manganite (LSM) cathode of solid oxide fuel cells (SOFCs) has been characterized using focused ion beam (FIB) and scanning electron microscopy(SEM) combined with image processing. Two-point correlation functions of the two-dimensional (2D) images taken along the direction of porosity gradient are used to reconstruct a three-dimensional (3D) microstructure. The effective elastic modulus of the two-phase porosity-graded cathode is predicted using strong contrast (SC) and composite inclusion (CI) homogenization techniques. The effectiveness of the two methods in predicting the effective elastic properties of the porositygraded LSM cathode is investigated in comparison with the results obtained from the finite element model (FEM).

25 ENERGY STORAGE↗
DOE OSTI2026

A multi‐variable framework for selecting WRF physics configurations at convection‐permitting scales: An Amazon wet‐season case study

Tropical convection over rainforests modulates atmospheric circulation and the energy and hydrological cycles across multiple scales. However, the scarcity of observations still limits our understanding of these processes. Although numerical models are utilized to investigate atmospheric physical processes, their performance depends on the choice of parameterizations and grid resolution. Here, in this work, we introduce and apply a multi‐variable, multi‐physics framework to evaluate and rank the Advanced Research Weather Research and Forecasting (WRF–ARW) configurations at 1‐km resolution over the central Amazon during the wet season. A 48‐member ensemble combines three land‐surface models (LSMs), four planetary boundary layer (PBL), and four microphysics (MP) schemes. Model performance for seven convection‐related near‐surface and boundary‐layer variables is assessed using Taylor diagrams and the Taylor skill score (TSS), analysis of variance (ANOVA)‐based sensitivity metrics, and non‐parametric rank tests. We then construct a combined, weighted TSS to identify configurations that are comparatively robust across variables. Results showed that most configurations reproduce near‐surface temperature, sensible and latent heat fluxes, and boundary‐layer height reasonably well, whereas humidity and rainfall remain challenging. LSM choice has the strongest impact on the surface fluxes and a secondary influence on near‐surface temperature and humidity, PBL schemes dominate boundary‐layer height, and MP schemes exert the largest control on rainfall. No single configuration is optimal for all variables, but the combination of Noah (LSM), Yonsei University (PBL), and Morrison (MP) emerges as the most robust configuration for this case, with the WRF single‐moment six‐class scheme (WSM6) providing a competitive, computationally cheaper MP alternative. The framework is general and can be applied to other regions, seasons, and convective regimes.

Amazon rainforest↗
DOE OSTI2024

Offshore application of landslide susceptibility mapping using gradient-boosted decision trees: a Gulf of Mexico case study

Abstract Among natural hazards occurring offshore, submarine landslides pose a significant risk to offshore infrastructure installations attached to the seafloor. With the offshore being important for current and future energy production, there is a need to anticipate where future landslide events are likely to occur to support planning and development projects. Using the northern Gulf of Mexico (GoM) as a case study, this paper performs Landslide Susceptibility Mapping (LSM) using a gradient-boosted decision tree (GBDT) model to characterize the spatial patterns of submarine landslide probability over the United States Exclusive Economic Zone (EEZ) where water depths are greater than 120 m. With known spatial extents of historic submarine landslides and a Geographic Information System (GIS) database of known topographical, geomorphological, geological, and geochemical factors, the resulting model was capable of accurately forecasting potential locations of sediment instability. Results of a permutation modelling approach indicated that LSM accuracy is sensitive to the number of unique training locations with model accuracy becoming more stable as the number of training regions was increased. The influence that each input feature had on predicting landslide susceptibility was evaluated using the SHapely Additive exPlanations (SHAP) feature attribution method. Areas of high and very high susceptibility were associated with steep terrain including salt basins and escarpments. This case study serves as an initial assessment of the machine learning (ML) capabilities for producing accurate submarine landslide susceptibility maps given the current state of available natural hazard-related datasets and conveys both successes and limitations.

Dyer, Alec S. (ORCID:0000000219813904)↗
DOE OSTI2020

Combined Cr and S poisoning behaviors of La 1-x Sr x MnO 3±δ and La 1-x Sr x Co 1-y FeyO 3-δ cathodes in solid oxide fuel cells

Although the individual effects of airborne Cr and S contaminants on SOFC cathode performance degradation have been extensively studied, the combined effects of Cr and S contaminants remain largely unexplored. Under the real SOFC operating condition where the Cr and S species coexist, their effects may compete, affecting the poisoning behavior. Here, our investigation reveals that the combined Cr and S poisoning behavior of LSCF remains different from those of individual Cr and S poisonings, while the combined poisoning mechanism of LSM is equivalent to the sum of those of individual Cr and S effects. For LSCF electrode, gaseous Cr species are deposited mainly at the LSCF/GDC interface by electrochemical reduction, rather than forming SrCrO 4 on LSCF surfaces (as in the case of Cr-only poisoning), indicating no reaction between Cr vapors and SrO on the LSCF surface. Thermodynamic analysis demonstrates that the SrO on LSCF surface absorbs SO 2 (g) and thereby loses the Cr-gettering effect, allowing Cr vapors to flow through LSCF and to reach the LSCF/GDC interface where the Cr deposition occurs. Unlike LSCF, LSM electrode shows cumulative effects of Cr and S, as Cr accumulation occurs at the triple-phase boundary and S absorption takes place at localized Sr-rich regions.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Quantifying physical parameterization uncertainties associated with land-atmosphere interactions in the WRF model over Amazon

The Weather Research and Forecasting (WRF) model can be used to diagnose regional land-atmosphere (L-A) coupling strength in the absence of sufficient observations but subjected to uncertainties associated with model physical parameterizations. In this study, we propose a framework to quantify and reduce model physical parameterization uncertainties associated with surface fluxes and L-A coupling. An ensemble of WRF simulations with different physical schemes is used to simulate surface fluxes and land-atmosphere coupling strength over the Amazon region. The physical parameterizations investigated include cloud microphysics (MP), land surface processes (LSM), planetary boundary layer (PBL), surface layer (SL), and cumulus (CU). We perform 120 ensemble simulations using the WRF model and different combinations of six MPs, three LSMs, six PBLs and SLs and three CUs. The measurements from the GoAMAZON field campaign and satellite data are used to evaluate model performance. A Multi-way analysis of variance (ANOVA) approach is applied to quantify the relative importance of different physics processes on L-A coupling. The Tukey’s test is used to sort schemes that have no significant differences into one group. The suite of physics that result in the best simulations of the corresponding variables are selected based on the Taylor skill score. Results show that the relative importance of processes and their interaction vary with the variables of interest. For example, CU was the most important process in modulating soil moisture, 2 m-humidity, latent heat, and net radiation. LSM showed dominant effects on 2 m-temperature and also has the largest impact on sensible heat and the lifting condensation level. The best physical parameterization ensembles show much narrower ranges of the variables of interest than the priori ensemble. Results of this study show the roles of different physical processes in modulating L-A interactions, quantify model uncertainties from physical processes, and provide insights for improving the model physics parameterizations.

Wang, Chen↗
DOE OSTI2021

A novel solid oxide electrolytic cell with reduced endothermic load for CO 2 electrolysis using (La 0.80 Sr 0.20 ) 0.95 MnO 3-δ cathode

CO 2 conversion to CO via solid oxide electrolysis provides a potentially efficient method for converting CO 2 into an industrially relevant product. A solid oxide electrolysis cell with (La 0.80 Sr 0.20 ) 0.95 MnO 3-δ (LSM) as the CO 2 reduction cathode, yttrium stabilized zirconia (YSZ) as electrolyte, and nickel as the H 2 oxidation anode was operated 800 °C and 850 °C. Thermogravimetric analysis of the LSM material showed no catalyst oxidation at operating temperatures allowing for CO 2 electrolysis without reducing safe gas. In addition, no cathode material mass gain was observed in the presence of CO suggesting little to no carbon deposition occurred above 750 °C. The formation rates of CO for the cell reached 1.15 mL∙min-1∙ cm -2 for an applied current of 150 mA∙cm -2 achieving a faradaic efficiency of 100 %. Furthermore, the cell displayed good stability in the short-term CO 2 electrolysis test with a nominal voltage drop of 4 mV h -1 for 10 h at 850°C. This study shows the feasibility of operating a solid oxide CO 2 electrolysis cell for CO production with H 2 at the anode to reduce endothermic process load.

(La0.80Sr0.20)0.95MnO3-δ↗
DOE OSTI2019

Enhancing Oxygen Exchange Activity by Tailoring Perovskite Surfaces

A detailed understanding of the effects of surface chemical and geometric composition is essential for understanding the electrochemical performance of the perovskite (ABO 3 ) oxides commonly used as electrocatalysts in the cathodes of ceramic fuel cells. In this work, we report how the addition of submonolayer quantities of A- and B-site cations affect the rate of the Oxygen Reduction Reaction (ORR) of Sr-doped LaFeO 3 (LSF), LaMnO 3 (LSM), and LaCoO 3 (LSCo). Density functional theory (DFT) calculations were performed to determine the stability of different active sites on a collection of surfaces. With LSF and LSM, rates for ORR are significantly higher on the A-site terminated surface, while surface termination is less important for LSCo. Our findings highlight the importance of tailoring the surface termination of the perovskite to obtain its ultimate ORR performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Impact of Lateral Flow on Surface Water and Energy Budgets over the Southern Great Plains – A Modeling Study

As we see the horizontal grid spacing decrease, treatment of hydrologic processes in land surface models, such as the lateral flow of surface and subsurface flow, need to be explicitly represented. Unlike previous studies that mainly focused on the mountainous regions, in this study the offline WRF-Hydro model is employed to study the impact of lateral flow on soil moisture and energy fluxes over the relatively flat southern Great Plains (SGP). The vast amount of measurements over the SGP provide an unique opportunity to assess the model behavior. In addition, newly developed land surface properties and input forcing are ingested into the model, in an attempt to reduce uncertainties associated with the initial and boundary forcing and help to identify model deficiencies. Our results show that the more realistic inputs (parameters, soil types, forcing) lead to larger underestimation of latent heat flux and dry bias, indicating the existence of model structural uncertainty (embedded errors) in WRF-Hydro that need to be characterized to inform future model development efforts. Including lateral flow processes partly mitigates the model deficiencies in representing hydrologic processes and alleviates the dry bias. In particular, both surface and subsurface lateral flow increase soil moisture mainly over the lower elevations, except that subsurface flow also affects soil moisture over steeper terrains. Additional simulations are performed to assess the effect of routing resolution on model results. When LSM resolution is high, noticeable differences in soil moisture are produced between different routing resolutions especially over steep terrain. Whereas when LSM resolution is coarse, differences between routing resolutions become negligible, especially over flat terrain.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Evaluation and Optimization of Snow Albedo Scheme in Noah-MP Land Surface Model Using In Situ Spectral Observations in the Colorado Rockies

The Biosphere-Atmosphere Transfer Scheme (BATS) ground snow albedo algorithm is commonly used in land-surface models (LSM), weather forecasting and research applications. This study addresses key uncertainties in BATS simulated ground snow albedo within the Noah-MP LSM framework through evaluation and optimization of the Noah-MP BATS ground snow albedo formulation using 2-band (visible and near-infrared (NIR)) in situ albedo observations at Rocky Mountain field stations. The Noah-MP BATS ground snow albedo scheme is extremely sensitive to its input parameters. Namely, an ensemble generated by varying BATS input parameters within potentially plausible ranges provides an average daily range (maximum ensemble member minus minimum ensemble member) of ground snow albedo exceeding 0.45 in visible and NIR bands. Parameter optimization improves agreement between simulated and in situ observed ground snow albedo in visible, NIR and broadband spectrums. Importantly, optimized parameters result in reduced biases relative to observed fresh-snow albedo and better agreement with observed albedo decay. Our analysis across different sites supports that the optimized BATS ground snow albedo parameters are appropriate to transfer in space and time, at least within the region studied (the central-southern Rocky Mountains). The primary error source remaining after parameter optimization is that observed fresh-snow albedo is highly variable, particularly in the NIR spectrum, whereas BATS fresh-snow albedo is constant, an issue which requires further investigation. This study shows significant correlations between observed fresh-snow albedo and surface meteorological conditions (e.g., downward shortwave radiation and temperature) which can support future model development that attempts to include a time-varying formulation for fresh-snow albedo.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Simultaneously improved reversibility and hydrogen production of solid oxide cells through infiltrating air electrode

Among the various fuel cells, solid oxide cells (SOCs) are the unique type that can principally operate reversibly as either fuel cells to produce electricity or as an electrolyser to split water and produce green hydrogen (H 2 ). Nevertheless, the SOCs' reversibility presents enormous challenges that are manifested by the fast degradation through the cycling between fuel cell and electrolysis mode. While the La 0.8 Sr 0.2 MnO 3 /yttria-stabilized zirconia (LSM/YSZ) air electrode possesses significant advantages in terms of high electrical conductivity and high thermal stability under fuel cell mode, the SOCs with the LSM/YSZ air electrode experience rapid performance degradation with catastrophic electrode delamination shortly after switching from fuel cell to electrolysis mode. To prevent such catastrophic delamination and enable the electrolysis H 2 production, a chemical solution with the designed chemistry of SrFe 2 O 4-d was infiltrated into the LSM/YSZ air electrode. The infiltration immediately mitigates the catastrophic delamination, and the infiltrated cells exhibit significantly improved reversibility upon the electrochemical operation. Nanostructure examination reveals nanoscale cracks and second-phase nanograins formed in the air electrode from the baseline cell. By contrast, no delamination was observed at either the micron or the nanoscale for the infiltrated cell, which is attributed to the increased ion conductivity of the Fe-doped LSM mixed conductor induced by the significant interdiffusion between the LSM backbone and infiltrates. Here, this study presents a viable method for preventing electrode delamination while enhancing the durability of H 2 production and power generation for reversible fuel cell/electrolysis cell operation. It further opens new research directions of modifying the electrochemical activity of the electrode of inherently functional cells through the infiltration of the solutions with different chemistry.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

First-principles thermodynamic assessment of Sr-containing secondary phase formation in strontium-substituted lanthanum manganites for solid oxide cell applications

Sr-secondary phase formation is a potentially significant degradation mode with direct impact upon solid-oxide cell (SOC) commercial viability. A first-principles based thermodynamic study was performed for La 1−x Sr x MnO 3±δ (LSM) perovskites to assess their stability against formation of different Sr-secondary phases, including SrO, SrCrO 4 , SrSO 4 , SrCO 3 , and Sr(OH) 2 , for SOC applications. The Sr-secondary phase formation reaction free energies were determined via a thermodynamic model by combining ab initio lattice dynamics calculations for the solid phases and ab initio thermodynamic data for the gas phases. The current approach expands the previously reported thermodynamic modeling studies by integrating first-principles based point defect equilibria into the thermodynamic analysis. The modeling results obtained using this new approach indicate an increased tendency to form the SrO oxide upon decreasing the oxygen partial pressure. Additionally, the enhancing factors to form the Sr-related secondary phase from the associated SrO activity in LSM are further quantified by considering the equilibrium of SrO reacting with the contaminant gas species as a function of temperature and pressure.

defect thermodynamics modeling↗
DOE OSTI2010

Possibilities For The LAGUNA Projects At The Frejus Site

The present laboratory (LSM) at the Frejus site and the project of a first extension of it, mainly aimed at the next generation of dark matter and double beta decay experiments, are briefly reviewed. Then the main characteristics of the LAGUNA cooperation and Design Study network are summarized. Seven underground sites in Europe are considered in LAGUNA and are under study as candidates for the installation of Megaton scale detectors using three different techniques: a liquid Argon TPC (GLACIER), a liquid scintillator detector (LENA) and a Water Cerenkov (MEMPHYS), all mainly aimed at investigation of proton decay and properties of neutrinos from SuperNovae and other astrophysical sources as well as from accelerators (Super-beams and/or Beta-beams from CERN). One of the seven sites is located at Frejus, near the present LSM laboratory, and the results of its feasibility study are presented and discussed. Then the physics potential of a MEMPHYS detector installed in this site are emphasized both for non-accelerator and for neutrino beam based configurations. The MEMPHYNO prototype with its R and D programme is presented. Finally a possible schedule is sketched.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

Investigations of 2β decay of {sup 106}Cd and {sup 58}Ni with HPGe spectrometer OBELIX

Investigations of double beta decay processes to excited states of daughter nuclei were performed at the Modane underground laboratory (LSM, France, 4800 m w.e.) using the high sensitivity spectrometer OBELIX [1], which is a common activity of JINR Dubna, IEAP CTU in Prague and LSM. The spectrometer is based on the HPGe detector with the sensitive volume of 600 cm{sup 3} and relative efficiency of 160%. Investigation of resonant neutrino-less double electron capture of {sup 106}Cd was performed with ∼23.2 g of {sup 106}Cd (enrichment of 99.57%) during ∼17 days. The experiment with natural Ni (∼21.7 kg of mass) was also carried out during ∼47 days. The preliminary experimental limits for 0νEC/EC resonant decay to the excited states of {sup 106}Pd and different modes of β β decay {sup 58}Ni are presented.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

The DAMIC-M Low Background Chamber

The DArk Matter In CCDs at Modane (DAMIC-M) experiment isdesigned to search for light dark matter (m$_{χ}$ < 10 GeV/c$^{2}$)at the Laboratoire Souterrain de Modane (LSM) in France. DAMIC-Mwill use skipper charge-coupled devices (CCDs) as a kg-scale activedetector target. Its single-electron resolution will enable eV-scaleenergy thresholds and thus world-leading sensitivity to a range ofhidden sector dark matter candidates. A DAMIC-M prototype, the LowBackground Chamber (LBC), has been taking data at LSM since2022. The LBC provides a low-background environment, which has beenused to characterize skipper CCDs, study dark current, and measureradiopurity of materials planned for DAMIC-M. It also allows testingof various subsystems like readout electronics, data acquisitionsoftware, and slow control. This paper describes the technicaldesign and performance of the LBC.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗